The present invention relates to a hollow metal golf club head and a method for manufacturing the same, more particularly to a structure of the crown portion capable of increasing the carry distance of the struck ball.
In recent years, in order to increase the traveling distance (carry and run) of the struck ball, various propositions to improve the rebound performance of the head by increasing the coefficient of restitution of the face portion have been proposed for the wood-type golf club heads.
U.S. Pat. No. 7,096,558 discloses a wood-type hollow metal head which comprises: a main body provided with a front opening and formed by lost-wax precision casting; and a face plate provided with a turnback and formed by hot forging a metal material so as to improve the rebound performance and the durability of the face portion.
U.S. Pat. No. 6,989,506 discloses a wood-type golf club head (FIG. 9) which comprises: a main body made of a metal material and provided with a top opening and a front opening; a face plate made of a metal material and covering the front opening; and a crown plate made of a metal material and covering the top opening. The face plate and crown plate are welded to the main body by utilizing laser welding to improve the joint strength.
On the other hand, the current USGA golf rule limits the coefficient of restitution (COR) of a head such that the COR cannot be higher than 0.830. Therefore, we can not adopt a means of increasing the coefficient of restitution over the above limitation in order to increase the traveling distance of the struck ball.